In case of a breakdown of a motor vehicle, especially in the case when certain defects affect the drive train in a way that the hydraulic pressure cannot establish itself in the automatic transmission, the parking lock, as a general rule, is automatically activated. It is necessary, for the purpose of the recovery or the relocation of the concerned vehicle, to deactivate the automatically activated parking lock, which usually takes place manually by trained personnel, using special tools, certain kinematics, and forced power activated systems.
In accordance with the state of the art, the activating systems for an emergency release of the parking lock in an automatic transmission are positioned in the transmission, as well as in the vehicle, such that their integration into the drive train has significant limitations, especially in regard to the required installation space and the design options of the drive train and its surrounding chassis contour.
A shifting mechanism is known through DE 4317257 C1 and comprises an electric motor which is used for activation of the selector slide, spring energy is used to engage the parking lock, as well as a mechanical emergency release which can be operated by the driver in case of a breakdown of a hydraulically operated parking lock release, by way of the lock bar, the parking lock is activated via a specially designed connectivity rod which has a guiding groove.
A parking lock of an electro-hydraulic control mechanism of an automatic transmission is also known to the applicant through DE 4322523 A1, which can be engaged via spring energy and can be disengaged by means of oil pressure, by way of a mechanical emergency release mechanism, comprising a lever, mechanically coupled with the parking lock, which can be operated by the driver through a Bowden cable for the emergency release of the parking lock.
The applicant is aware, through DE 19643303 A1, of an emergency release mechanism for a parking lock which comprises a spring energy store in which the energy can be released via rotation of the ignition key in the ignition lock of the vehicle, to release the parking lock.
In addition and through DE 19643304 A1, the applicant is aware of an emergency release mechanism of a parking lock, which is operated via the already present brake of the vehicle. Also, through DE 19643812 A1, the applicant has knowledge of a parking lock of an automatic transmission, in which an electronic transmission control device determines, via an electromagnetic valve, the position of a spring load, whereby the spring load is mechanically linked with a parking handle and with an emergency release.
In accordance with the description in DE 19834074 A1, the applicant is aware of a device for the release of a parking lock for an automatic transmission, in which the parking lock is activated via a spring load and again deactivated via the transmission control by means of the system pressure, whereby, in case of a failure of the system pressure or the failing transmission control, the parking lock can be released via a pump from within the passenger compartment, by activating a lever, preferably the hand brake lever.
Known to the applicant through DE 19837832 A1 is a parking lock with an emergency release mechanism, which comprises a manual activating mechanism, which rotates an emergency release disc in such a way that a pin causes the rotation of the detent disc and thereafter engages into a lock which keeps the parking lock in the released position.
Also, known to the applicant through DE 19848733 A1 is a mechanism for the emergency release of a parking lock, whereby the parking lock is released by the activation of an externally accessible towing device, which resides outside of the motor vehicle, and the related axial movement of the operational connection between the towing device and a release mechanism at the transmission.
Known to the applicant through DE102004030006 A1 is a linear piston system for the hydraulic release of a parking lock under normal operation, with a holding magnet, or an electromagnetically securable locking mechanism respectively, to hold the piston, or the piston rod respectively, in a locked position, as well as with a manually activated emergency activating mechanism to lock and to unlock, from the outside, the parking lock in an emergency operation, whereby the emergency activating mechanism interacts with a sloping groove, and simultaneously moves the piston rod axial, when activating the emergency mechanism coaxially to the piston rod, and thereby rotates by a defined angle and locks into the associated end position. Additional mechanisms for emergency the release of a parking lock of an automatic transmission are mentioned, for example, U.S. Pat. Nos. 3,116,815 A and 2,963,115 A.
Also, a drive step selecting mechanism arises from the DE 19962243 A1, for selecting at least the automatic transmission operating steps “D”, “N”, “R”, “P” of an automatic motor vehicle transmission, which can be selected by the driver via a control mechanism and which will be engaged through a transmission control mechanism which drives an electro hydraulic actuator, whereby an engaged parking lock, in the operating position “P”, can be disengaged by the driver via an operating mechanism, in particular a hand lever, which actuates a release mechanism in the automatic transmission enclosure. The operating mechanism is connected, via a Bowden cable, with the release lever of the release mechanism, which is firmly installed on an axle which, during engagement and disengagement of the parking lock, rotates back and forth due to the electro-hydraulic actuating devices and thus pivots the unlocking lever back and forth. In addition and in accordance with DE 19962243 A1, the pivoting motion of the unlocking lever is not transmitted to the Bowden cable because the unlocking lever can move along its stranded Bowden wire which it is hooked to; a form fit between the stranded Bowden wire and the unlock lever, through a thickened area of the stranded Bowden wire, is only achieved when the operating mechanism is actuated.